Gregory O'Sullivan is named as the secretary of the Aer Lingus ESOT and also sits on the board as a director of the IAPP.

A source close to Aer Lingus this weekend said that O'Sullivan recused himself of involvement in both boards immediately after the Ryanair offer for Aer Lingus became known.

However, the same source confirmed that O'Sullivan remains a member of both boards and no alternate has been nominated to act in his place on either.

While the Aer Lingus employee share ownership trust has so far remained tight-lipped on the takeover battle, the IAPP began acquiring stakes in Aer Lingus within days of Ryanair announcing its bid to wrestle ownership of the newly quoted company.

The Aer Lingus ESOT was described last week as being the "kingmaker" in the takeover battle. It holds a 14.9% stake in Aer Lingus, when options to acquire more stock are included. As such it holds an important position in determining the outcome of Ryanair's bid. The ESOT could combine forces with the IAPP, and new shareholder Denis O'Brien who has a 2.1% stake, to strangle Ryanair's plans. Their amalgamated current holdings stand at over 19.2%. The IAPP has so far spent over 30m buying stock in Aer Lingus since Ryanair revealed it would make a formal bid for the company.

Last week NCB analyst John Sheehan said in a Ryanair note that the ESOT/employees are key to the offer as their response will "heavily influence" the government's stance.

The Irish Pensions Board said last week that it has cautioned the IAPP that its funds must only be used for the betterment of its members' future pensions and that it would be monitoring any further share purchases the pilots' pensions fund makes.